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Connection between liquid and non-crystalline solid phases in water
Fausto Martelli1, Fabio Leoni2, Francesco Sciortino3
1IBM Research Europe, Hartree Centre, Daresbury WA4 4AD, United Kingdom.
The Journal of Chemical Physics
|September 16, 2020
Summary
Researchers used a Neural Network to study water
Area of Science:
- Physical Chemistry
- Materials Science
- Computational Chemistry
Background:
- Water exhibits anomalous behavior in its supercooled liquid state.
- This region is experimentally challenging to study, known as 'no-man's land'.
- Distinct amorphous solid forms (low-density amorphous and high-density amorphous ices) exist.
Purpose of the Study:
- To investigate the microscopic origins of water's anomalies.
- To explore the connection between amorphous solid states and supercooled liquid water.
- To understand the behavior in the 'no-man's land' region of the phase diagram.
Main Methods:
- Development of a Neural Network scheme to analyze local structures.
- Application of the scheme across a wide range of the water phase diagram.
- Analysis of structural features beyond simple tetrahedrality.
Main Results:
- Local structures characteristic of low-density amorphous (LDA) and high-density amorphous (HDA) ices are present in supercooled liquid water.
- The prevalence of LDA-like structures correlates with regions of maximum thermodynamic fluctuations, linked to water's anomalies.
- HDA-like structures become dominant at high pressures.
Conclusions:
- Both LDA and HDA are confirmed as genuine glassy states of water.
- A microscopic link is established between the non-equilibrium and equilibrium phase diagrams of water.
- The study provides insights into the structural basis of water's unique properties.
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